Curable silicone compositions giving optically clear silicone products are frequently used in light emitting devices for properties such as their thermal and light resistance. Such curable silicone compositions may have advantages of high reliability over conventional materials such as epoxy resin materials, which may suffer from the drawback of discoloration by the action of heat and light generated from the light source.
However, mechanical and adhesion properties of optically clear silicone products may be poorer than epoxy resins and filled silicones. These may cause fracture or delamination of the silicone product, resulting in a drop of the light output. One proposed approach to address this is to use a silicone resin compatible to the silicone product as a toughening agent. Another approach is to incorporate organic polymer components or functionalities into the silicone polymer structure, however, such modifications of silicone may be unsuitable for thermal and light resistance.